Inhibited oil



Patented Mar. 25, 1947 INHIBITED OIL.

Arthur W. Lewis, I'lainfleid, N. J., and John E. Schott, New York. N.Y., assignors to Tide Water Associated Oil Company, Bayonne, N. 1., acorporation 01' Delaware No Drawing. Application August 16, 1944, S9118]N0. 549,794

11 Claims. (Cl. 252-42.?)

The present invention relates to oil compositions, and more particularlyto improved lubricating compositions containing as a major constituent amineral lubricating oil and relatively minor amounts of substanceseflective to counteract or inhibit certain objectionable reactions. Theinvention is primarily directed to a motor oil 01' crankcase lubricantwhich possesses the unique combined characteristics of providingeifective detergent properties, satisfactory motor lubrication andprotection of certain motor parts against corrosion during extended useof the motor, and of preserving or protecting metal surfaces of motorparts against rusting during periods prior to use, as during periods ofextended idleness.

Internal combustion engines of modern design are capable of carryingconsiderably greater loads than was formerly the case with the oldertype engines. This increased load-carrying capacity and the increasedseverity of engine operating conditions incident thereto necessitatesemployment of special lubricants, Many of the more modern engines areequipped with hard alloy-type bearings. such as copper-lead alloy, whichcarry greater loads than Babbitt bearings, but which are subject torapid corrosion under engine operating conditions. Likewise, thetendency towards deposition of sludge upon rings, ring grooves, pistonsand other operating parts, with resulting impairment of engineefficiency, is characteristic in the operation of modern engines.

These difficulties, and others accompanying the advent of modern motorsof increased power, have been combatted by incorporation, in crankcaselubricants, of substances acting to inhibit corrosion of alloy-typebearings and sludge deposition. In recent years many such additives havebeen proposed for use in motor oils.

More recently, and particularly during the present war, a seriousdifiiculty has arisen in connection with rusting of internal engineparts which prior to use are put into storage in humid atmospheres, orwhich are subjected to salt water atmospheres as during transportationoverseas. Under such conditions cylinder walls and other ferrous metalparts become rusted, necessitating dismantling for rust removal andoften extensive rebuilding or part replacement before the motor can beput into its intended service. This is especially serious regardingcombat vehicles and other motorized equipment needed for immediate useupon arrival at destination.

Although many motor oils containing sub.

stances intended to inhibit corrosion of alloytype bearings and todecrease sludge deposition during motor operation were available priorto this invention, they would not satisfactorily inhibit rusting ofmotor parts under the stated stortge and transportation conditions. Useof slushing compounds for this purpose was unsatisfactory since themotor could not be run without danger of bearing corrosion or formationof harmful deposits, and dismantling oi the motor to remove the slushingcompound usually was required prior to motor operation,

A primary object of the present invention is to provide crankcaselubricant compositions having the dual function or inhibiting rusting oiengine parts and forming satisfactory lubricants for use in modernengines.

Another important object is the provision of a motor lubricating oilcapable of inhibiting corrosion of alloy-type bearings when used as acrankcase oil in motor operation and capable of inhibiting rusting offerrous metal motor surfaces during periods of motor idleness.

A further object is to provide an improved rust-inhibiting composition.

A still further object is to provide an improved mineral oil lubricantcomposition.

Early in the experimental research work leading to this invention it wasdiscovered that, in general, substances which can be dissolved inhydrocarbon lubricating oils and which are effective to inhibitalloy-type bearing metal corrosion, not only are ineffective againstrustformation on motor parts, but are mutually incompatible with many knownrust-inhibiting agents, and tend to depreciate the effectiveness of thelatter-named agents when present therewith in fnotor oil. Likewise, mostsubstances added to motor oil for the purpose of protecting againstrusting result in an increased tendency towards bearing corrosion; Inaddition to.these incompatibilities, it was found that many compoundsselected for rust-inhibition caused instability of motor oils in otherrespects, such as causing foaming, sludge deposition in service, orother undesirable effects.

According to the present invention, in broad aspect, it has beendiscovered that sulfonic acid derivatives, and more particularlyoil-soluble salts of sulfonic acid compounds derived from petroleum,such as oil-soluble alkali metal and alkaline earth metal salts ofmahogany acids, are eflective rust inhibitors; and in more specificaspect that hydrocarbon lubricating oil compositions containingregulated proportions of such substances together with regulated andrelated proportions of certain materials of alloy bearing corrosioninhibitor eiiectiveness are admirably suited for the dual purpose ofeffectively lubrieating modern internal combustion engines in serviceand preventing the above-described rusting of metal parts prior to themotor service period and during periods of idleness.

An important feature of the invention resides in the discovery of acomposite additive for motor oils comprising, as one component, asuitable rust-inhibitor oi the class stated and, as another component,an effective agent inhibiting alloytype bearing corrosion. 01' equal orgreater importance is the discovery that these two components aremutually compatible and may be used in suitable hydrocarbon lubricatingoil without resulting in the objectionable effects stated above. In thisregard it has been found that oil compositions of this invention besidesfunctioning to inhibit rusting and bearing corrosion possess excellentdetergent properties, in most instances satisfactorily low foamingcharacteristics and other characteristics desired in a motor lubricantof the type here concerned.

The component incorporated in the lubricants of this invention primarilyfor the purpose of inhibiting bearing corrosion may be certain organiccompounds containing both sulfur and phosphorus, more particularly metalsalts of compounds resulting from reacting phosphorus pentasulflde withaliphatic or cycle-aliphatic alcohols. These compounds arethiophosphoric acid esters, apparently metal (dl-aliphatic or dicycloaliphatic) dithio phosphates. alkyl substituted groups. One example iszinc dl(methyl cyclohexyl) dithiophosphate. Such compounds, whileeil'ective as bearing corrosion inhibitors, are ineffective forpreventing rusting of ferrous metal motor parts under the conditionsstated above, and, in fact, they tend to promote rusting under certainconditions. However, when these compounds are present in suitablehydrocarbon oils along with the stated sulfonates in controlled andbalanced amounts, their rust-promoting tendencies are eliminated. Thus,the two components of the inhibitor mutually coact or exhibitinterdependence in the lubricant composition.

For motor lubricating oils, minor amounts of the inhibitor components ascompared to the amount of hydrocarbon oil present may be employed withsatisfactory results. For example, it is seldom necessary to use, in theoil, more than 1 or 2% of the phosphate ester in order to secureadequate protection against bearing corrosion. Usually less than 1% isadequate. Minimum effective amounts of the phosphate ester will varysomewhat with diflerent oils used and with the particular salt orderivative employed. In general, when using the zinc salts mentionedabove at least about 0.2% by weight should be incorporated forlubricating oils from Pennsylvania crude and slightly less than thisamount as a minimum for those from Mid-Continent crudes.

As indicated, the ratio or balance between the amount of phosphate esterderivative component and the amount of sulfonate component present inthe motor oil of this invention is important and must be controlled. Theproportional amount of the sulfonate will vary directly with the amountof phosphate ester present. and in any event sufilcient of the formermust be incorporated to overcome the rust-promoting tendency of thelatter, and to inhibit rusting of the ferrous metal surfaces in motorsin which the lubricant is to They may contain be employed. In mostinstances the amount of sulfonate component should be such that theratio of sulfonate to phosphate ester is at least about 4 to 1. Ratiosranging up to about 10 to 1 have given good results, and higher ratios,as, for example, 12 to 1, may be used if desired. Too littleof thesulfonate with respect to the amount of phosphate ester present willresult in rusting of ferrous metal motor parts, but a relatively smallexcess of sulfonate over that required to prevent rusting is notobjectionable in most instances. f

The following examples will serve to illustrate the invention in settingforth specific embodiments in the form of motor oils compounded forspecific usage conditions and possessing properties and qualificationsmeeting certain rigid tests to be described later herein. Inasmuch asother compositions, not necessarily meeting all of the test requirementsare included within the scope ofthe invention, the following examplesshould not be considered limitative.

Example I In a motor lubricating oil, derived from Mid- Contlnent crudeby solvent refining methods, there was dissolved 0.467% of the zinc saltof the reaction product of alkyl cyclohexanol and phosphoruspentasulflde (apparently di(alkyl cyclo-- hexyl) dithio phosphate), 1.1%of a calcium salt of mahogany acids, 2.06% of a sodium salt of mahoganyacids, and 0.7% of Paraflow. a wax alkylated naphthalene commonlyemployed as a pour depressant in lubricating oils. All percentages areby weight. The resulting compounded motor oil lubricant had thefollowing characteristics and analysis:

The motor oil of Example I was equivalent in viscosity to SAE 10, thisbeing largely determined by suitable selection of the base oil.

Example II In this instance the base oil employed was a blend consistingof 76% by volume of a solvent refined distillate lubricating oil fromEast Texas crude and 24% by volume of a refined lubricating oil of 230viscosity at 210 F. and viscosity index of 40. derived fromMid-Continent crude.

A motor lubricant was compounded, using th s base oil and having thefollowing composition by weight:

4.37% "Lubrizol 738" (analysis indicates 25% by weight calcium salts ofmahogany acids, 10.75% by weight of zinc salts of di(alkyl cyclohexyl)dithiophosphates, dissolved in petroleum oil as the remainingconstituent) 2.02% sodium salt of mahogany acids and, as the remainder,the base oil described in which the listed components were dissolved.

's The compounded motor oil of Example II was equivalent in viscosity toSAE 30 and further characterized as follows:

The compounded motor oil of this example consisted of the followinconstituents by weight:

0.8% of "Lubrizol 728" (analysis indicates 37.1% by weight of zinc saltsof thiophosphoric acid esters. presumably zinc salts of di(alkylcyclohexanyl) dithiophosphates, dissolved in petroleum oil as remainingconstituent).

2.79% of sodium salts of mahogany acids.

0.35% of Paraflow.

Remainder-Blend of solvent refined lubricating oils from Pennsylvaniaand Mid-Continent crudes.

This composition, equivalent to SAE 10, was characterized as follows:

A. P. I. gravity 28.7 Flash, C. O. C FL- 400 Pour F Viscosity (S. U. S.)

210 F 46.3 Viscosity index 99 Color, A. S. T. M 4 Ash per cent 0.43Carbon residue do 0.89 Sulfur do 0.36 Phosphorus do 0.03 Chlorine NilUnited States Army Ordnance Department Tentative Specification AXS-934(Rev. 1) of Oct. 13, 1943, entitled "Oil, Engine, Preservative"describes certain tests, each of which preservative engine oils mustpass to be accepted by the Army for use in the crankcases of motors forcombat use. Lubricant oils passing all of these tests are considered ofsatisfactory rustinhibiting and corrosion-inhibiting nature, as well ashaving other desired motor oil attributes. Such oils are installed inmotors shortly after assembly and may not be drained therefrom until themotor has been in operation for some time, thus eliminating necessityfor changing oil (and sometimes dismantling the motor to remove 'rust)between periods of storage or transportation and use. Before storage ortransportation the motors may be run-in," using these oils aslubricants, which results in coating of the draining the surfaces for 16hours at 130 F. and exposing the drained steel surfaces to an atmosphereof to relative humidity for 200 hours at 100 F. in a special humiditycabinet in such manner that moisture condenses on the said steelsurfaces. The oil is considered to have passed this test if after 200hours exposure at least one of the panels shows no corrosion and theother shows no more than a trace of corrosion. In addition, the freshlysanded steel panels after immersion in the test oil, draining, andexposure to synthetic sea water for 20 hours under specified conditionsmust not be corroded.

(2) Ability to neutralize acidic products of combustion in an engine.Freshly sanded steel panels, as above described, are dipped in 0.1%aqueous HBr solution and then the panels are alternately dipped in thetest oil and exposed to air. After exposure to the air for 4 hours underspecified conditions the panels must show no corrosion, staining orother attack if the test oil is to be considered as passed.

(3) Ability to withstand "C. L. R. Procedure for 36 Hour Engine Test forOxidation Characteristics of Heavy Duty crankcase Oil at a crankcasoiltemperature of 250 and 265 F., respectively, for two specified gradesof oil. In this test the oil is employed as lubricant in an internalcombustion engine containing alloy bearings under loaded conditions.Loss in weight of the alloy bearing as a. measure of corrosion occurringduring the run and the amount of sludge deposited on the piston and ringgrooves are indicative of the stability and inhibitor effectiveness ofthe test oil under intended use conditions.

(4) Volatile matter of less than 2.0% maximum.

(5) Excessive foaming of the oil must not occur under specified testconditions.

(6) Other requirements include viscosity and pour point limits andcompatibility with certain other oils.

Motor oil lubricants of this invention, illustrated in the aboveexamples, have successfully passed all of the AXS-934 tests. These oilshave proven satisfactory in protecting moderate engines against rustingunder relatively severe conditions during storage and transportationperiods, and in lubricating said engines in service following suchperiods.

In addition to the bearing corrosion and rust inhibitor substances setforth above, it is desirable in certain instances to have present in thecomposition a material of alkaline nature for the purpose of providingan alkaline reserve. Preferably such materials are amine compounds.Satisfactory results are obtained using, as this material, relativelylow molecular weight alkyi amines, such. for example. as amino methylpropanol. Relatively low proportional amounts, usually less than 1% byweight of the oil composition, are effective, the actual amounts whichcan be incorporated. as regards particular amines, being governed bytheir solubility in the oil employed. Motor oils having the compositionof those of the above examples to which have been added about 0.2% of2-amino 2-methyl l-propanol are quite satisfactory in this respect. Suchoils are contemplated within the scope of the invention.

We claim:

1. A composition suitable for lubricating modern engines comprising ahydrocarbon lubricating oil in major proportion, a minor proportion of athiophosphoric acid bearing corrosion inhibiting material and a sumclentamount of a sulfuric acid substance eflective in the composition toinhibit the rusting of ferrous metal motor parts, said sulionic acidsubstance and said bearing corrosion inhibiting material being presentin a weight ratio of not less than about 4 to 1.

2. A lubricant composition as defined in claim 1 in which the substanceeffective to inhibit rusting is a metal sulfonate selected from thegroup consisting of oil soluble alkali metal sulfonates and alkalineearth metal sulionates.

3. A lubricant composition adapted for the lubrication 01' internalcombustion engines equipped with alloy-type bearings comprising arefined petroleum lubricating oil, a bearing corrosion-inhibitingproportion of a suitable metal salt of the phosphorus andsuliur-containing reaction product obtainable by reacting an alcohol ofthe class consisting of aliphatic and cyclo-aliphatic alcohols withphosphorus pentasuifide, and a sufilcient amount of an oil-solublesulionate to inhibit rusting of ferrous metal engine parts contacted bysaid composition, said oil-soluble sulionate and said metal salt beingpresent in a weight ratio of not less than about 4 to 1.

4. A motor lubricant composition comprising a hydrocarbon lubricatingoil of motor oil character and a material effective to inhibit corrosionof alloy-type motor bearings and having rust-promoting tendency and anoil-soluble sulfonate rust-inhibiting agent in amounts eilective toinhibit rusting under humid atmospheric conditions of ferrous metalmotor surfaces to which the composition is applied, said ofl-solublcsulfonate and said material effective to inhibit corrosion of alloy-typemotor bearings being present in a weight ratio of not less than about 4to l.

5. A motor lubricating composition comprising a refined petroleumlubricating oil, an amount of a metal salt oi an organic thiophosphoricacid ester effective to inhibit alloy-type bearing corrosion and anoil-soluble metal sulfonate having rust-inhibiting properties, saidsulfonate and ester being present in the composition in a weight ratioof not less than about 4 to 1.

6. A motor lubricating composition comprising a refined petroleumlubricating oil, a, bearing corrosion inhibitor comprising a zinc saltof a thic- 8 phosphoric ester obtainable by reacting an alcohol oi thegroup consisting of aliphatic and cycloaliphatic alcohols withphosphorus pentasulfide, and an oil-soluble metal suli'onate havingrustinhibiting properties, said sulionate and said hearing corrosioninhibitor being present in the composition in a weight ratio of not lessthan about to l.

'l. A composition comprising a hydrocarbon oil. at least about 0.2 percent by weight of zinc diimethyl cyclohexyl) thio phosphate and anoilsoluble sodium salt or mahogany acids in an amount by weight at leastfour times the amount of said zinc salt present.

8. A composition as defined in claim 5, in which the suli'onate isselected from the group consisting of sodium and calcium salts oimahogany acids and a mixture of said sodium and calcium salts.

9. A motor lubricating composition comprising a refined petroleumlubricating oil, an amount of a zinc salt of the reaction productobtained by reacting an aliphatic or cyclo-aliphatic alcohol withphosphorus pentasulilde eflfective to inhibit alloy-type bearingcorrosion and a material eilective to inhibit ferrous metal corrosioncomprising sodium mahogany suiionate and calcium mahogany sulionate inamounts equivalent to from about 6 to about 10 times the amount of saidzinc salt present.

10. A composition as defined in claim 6 including an oil-solubleproportion 01 an organic amine.

11. A composition as defined in claim '7 including amino methyl propanoldissolved therein.

ARTHUR W. LEWIS.

JOHN E. SCHOTI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,261,047 .Assefl Oct. 28, 19412,182,992 Lebo Dec. 12, 1939 2,113,150 Wiezevich Apr. 5, 1938 2,369,632Cook et a1. Feb. 13, 1945 (Ilertii icate of Correction Patent No.2,417,876.

ARTHUR W. LEWIS ET AL.

March 25, 1947.

It is hereby certified that errors appear in the printed specificationof the above numbered patent reqinr ng correction as follows: Column 2,line 6, for stortge read storage; column 5, hne 6, for the numeral read10; column 6, line 47 for moderate" read modem' and that the saidLetters Patent should be read with corrections therem that the same mayconform to the record of the case in the Patent ese Signed andsealedthis 20th day'of May, A. D. 1947.

LESLIE FRAZER,

First Assistant flammisaioner of Patents.

material and a sumclent amount of a sulfuric acid substance eflective inthe composition to inhibit the rusting of ferrous metal motor parts,said sulionic acid substance and said bearing corrosion inhibitingmaterial being present in a weight ratio of not less than about 4 to 1.

2. A lubricant composition as defined in claim 1 in which the substanceeffective to inhibit rusting is a metal sulfonate selected from thegroup consisting of oil soluble alkali metal sulfonates and alkalineearth metal sulionates.

3. A lubricant composition adapted for the lubrication 01' internalcombustion engines equipped with alloy-type bearings comprising arefined petroleum lubricating oil, a bearing corrosion-inhibitingproportion of a suitable metal salt of the phosphorus andsuliur-containing reaction product obtainable by reacting an alcohol ofthe class consisting of aliphatic and cyclo-aliphatic alcohols withphosphorus pentasuifide, and a sufilcient amount of an oil-solublesulionate to inhibit rusting of ferrous metal engine parts contacted bysaid composition, said oil-soluble sulionate and said metal salt beingpresent in a weight ratio of not less than about 4 to 1.

4. A motor lubricant composition comprising a hydrocarbon lubricatingoil of motor oil character and a material effective to inhibit corrosionof alloy-type motor bearings and having rust-promoting tendency and anoil-soluble sulfonate rust-inhibiting agent in amounts eilective toinhibit rusting under humid atmospheric conditions of ferrous metalmotor surfaces to which the composition is applied, said ofl-solublcsulfonate and said material effective to inhibit corrosion of alloy-typemotor bearings being present in a weight ratio of not less than about 4to l.

5. A motor lubricating composition comprising a refined petroleumlubricating oil, an amount of a metal salt oi an organic thiophosphoricacid ester effective to inhibit alloy-type bearing corrosion and anoil-soluble metal sulfonate having rust-inhibiting properties, saidsulfonate and ester being present in the composition in a weight ratioof not less than about 4 to 1.

6. A motor lubricating composition comprising a refined petroleumlubricating oil, a, bearing corrosion inhibitor comprising a zinc saltof a thic- 8 phosphoric ester obtainable by reacting an alcohol oi thegroup consisting of aliphatic and cycloaliphatic alcohols withphosphorus pentasulfide, and an oil-soluble metal suli'onate havingrustinhibiting properties, said sulionate and said hearing corrosioninhibitor being present in the composition in a weight ratio of not lessthan about to l.

'l. A composition comprising a hydrocarbon oil. at least about 0.2 percent by weight of zinc diimethyl cyclohexyl) thio phosphate and anoilsoluble sodium salt or mahogany acids in an amount by weight at leastfour times the amount of said zinc salt present.

8. A composition as defined in claim 5, in which the suli'onate isselected from the group consisting of sodium and calcium salts oimahogany acids and a mixture of said sodium and calcium salts.

9. A motor lubricating composition comprising a refined petroleumlubricating oil, an amount of a zinc salt of the reaction productobtained by reacting an aliphatic or cyclo-aliphatic alcohol withphosphorus pentasulilde eflfective to inhibit alloy-type bearingcorrosion and a material eilective to inhibit ferrous metal corrosioncomprising sodium mahogany suiionate and calcium mahogany sulionate inamounts equivalent to from about 6 to about 10 times the amount of saidzinc salt present.

10. A composition as defined in claim 6 including an oil-solubleproportion 01 an organic amine.

11. A composition as defined in claim '7 including amino methyl propanoldissolved therein.

ARTHUR W. LEWIS.

JOHN E. SCHOTI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,261,047 .Assefl Oct. 28, 19412,182,992 Lebo Dec. 12, 1939 2,113,150 Wiezevich Apr. 5, 1938 2,369,632Cook et a1. Feb. 13, 1945 (Ilertii icate of Correction Patent No.2,417,876.

ARTHUR W. LEWIS ET AL.

March 25, 1947.

It is hereby certified that errors appear in the printed specificationof the above numbered patent reqinr ng correction as follows: Column 2,line 6, for stortge read storage; column 5, hne 6, for the numeral read10; column 6, line 47 for moderate" read modem' and that the saidLetters Patent should be read with corrections therem that the same mayconform to the record of the case in the Patent ese Signed andsealedthis 20th day'of May, A. D. 1947.

LESLIE FRAZER,

First Assistant flammisaioner of Patents.

